From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932120AbcGAJtf (ORCPT ); Fri, 1 Jul 2016 05:49:35 -0400 Received: from mail.skyhub.de ([78.46.96.112]:59877 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752302AbcGAJtH (ORCPT ); Fri, 1 Jul 2016 05:49:07 -0400 Date: Fri, 1 Jul 2016 11:23:01 +0200 From: Borislav Petkov To: Dave Hansen Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, ak@linux.intel.com, mhocko@suse.com, dave.hansen@linux.intel.com, luto@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/6] x86: fix duplicated X86_BUG(9) macro Message-ID: <20160701092300.GD4593@pd.tnic> References: <20160701001209.7DA24D1C@viggo.jf.intel.com> <20160701001210.AA77B917@viggo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160701001210.AA77B917@viggo.jf.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 30, 2016 at 05:12:10PM -0700, Dave Hansen wrote: > > From: Dave Hansen > > epufeatures.h currently defines X86_BUG(9) twice on 32-bit: > > #define X86_BUG_NULL_SEG X86_BUG(9) /* Nulling a selector preserves the base */ > ... > #ifdef CONFIG_X86_32 > #define X86_BUG_ESPFIX X86_BUG(9) /* "" IRET to 16-bit SS corrupts ESP/RSP high bits */ > #endif > > I think what happened was that this added the X86_BUG_ESPFIX, but > in an #ifdef below most of the bugs: > > [58a5aac5] x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled > > Then this came along and added X86_BUG_NULL_SEG, but collided > with the earlier one that did the bug below the main block > defining all the X86_BUG()s. > > [7a5d6704] x86/cpu: Probe the behavior of nulling out a segment at boot time > > Signed-off-by: Dave Hansen > Acked-by: Andy Lutomirski > Cc: stable@vger.kernel.org > --- > > b/arch/x86/include/asm/cpufeatures.h | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff -puN arch/x86/include/asm/cpufeatures.h~knl-leak-10-fix-x86-bugs-macros arch/x86/include/asm/cpufeatures.h > --- a/arch/x86/include/asm/cpufeatures.h~knl-leak-10-fix-x86-bugs-macros 2016-06-30 17:10:41.215185869 -0700 > +++ b/arch/x86/include/asm/cpufeatures.h 2016-06-30 17:10:41.218186005 -0700 > @@ -301,10 +301,6 @@ > #define X86_BUG_FXSAVE_LEAK X86_BUG(6) /* FXSAVE leaks FOP/FIP/FOP */ > #define X86_BUG_CLFLUSH_MONITOR X86_BUG(7) /* AAI65, CLFLUSH required before MONITOR */ > #define X86_BUG_SYSRET_SS_ATTRS X86_BUG(8) /* SYSRET doesn't fix up SS attrs */ > -#define X86_BUG_NULL_SEG X86_BUG(9) /* Nulling a selector preserves the base */ > -#define X86_BUG_SWAPGS_FENCE X86_BUG(10) /* SWAPGS without input dep on GS */ > - > - > #ifdef CONFIG_X86_32 > /* > * 64-bit kernels don't use X86_BUG_ESPFIX. Make the define conditional So I'd remove the "#ifdef CONFIG_X86_32" ifdeffery too and make that bit unconditional - so what, we have enough free bits. But I'd leave the comment to still avoid the confusion :) -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.